Help needed resolving DAX performance on parking events data coming from sensor system

Can you provide a pbix with example data so a specific solution can be suggested?  You may be able to get there with a DAX only change, but your solution is probably to make some data model changes.  DateTime columns mean high granularity and the potential for slow performance.  You might want to consider splitting your DateTime columns into separate Date and Time columns, and then adding a Date table and a Time table to your model, so you can iterate independently over both.  Another approach to consider is to "round" your DateTimes to the nearest 15 min, 30 min, etc. depending on the timeframe your care about in your analysis.

Pat